In general, a window grating of the above type is attached to predetermined parts of the wall surrounding the window opening to be firmly retained, so that there is concern that an accident occurs in an emergency of fire or the like, and also numerous accidents arose from such arrangement to date.
For the purpose of solving the problems of such conventional window gratings, there has previously been proposed an adapted window grating so constructed that one edge and the other edge are mounted pivotably and outwards turnably respectively on the corresponding window surrounding portions of the wall to enable fleeing through the window opening and the so opened grating. In addition, this known window grating is equipped at its turnable edge with a lock which is ordinarily fastened and opened with a key in case of an emergency as described above.
According to the above-mentioned known openable window grating, however, enough space is necessary for the pivoted edge to move outwardly. Such an open condition gives rise to difficulty in installation on window opening adjacent to a neighboring house, garden, trees or the like. Furthermore, such a lock as used with a key is a rather cumbersome one to open, so that there is an additional problem to open the locked wimdow grating easily and promptly.